Cylinder for turbine blades



May 8, 1928. V

J. F. JOHNSON CYLINDER FOR TURBINE BLADES Filed Oct. 8, 1925 WITNESSES: INVENTOR (5. J-F-Johnson ATTORN EY Patented May 8, 1928.

UNITED STATES JosIarr r. aomvson,

or swanrnmonn, rEnnsYLvaiqrA, assrenoa Fro wns'rme- HOUSE ELECTRIC 6t MANUFACTURING COMPANY CORPORATION OF PENNSYL- VANIA.

, oYLrnnEn roe TURBINE mamas.

Application filed October 8, 1925. SerialNo. 61,252.

My invention relates to elastic fluid turbines, more particularly to the blading and cylinder arrangement thereof, and has for its object the provision of apparatusof the character designated which shall afford an eiiicient path for the motive fluid and, at the same time, permit slight relative axial displacement between the stationary andmovingpartsof the turbine without undesirably affecting the operationthereof.

Apparatusembodying features of my in vention is illustrated in theaccomp'anying drawings forming a part of this specification in which: I p i i Fig. 1 is a fragmentary sectional view of a double flow turbine made in accordance with my invention; 1. a

Figs. 2, 3 and 4 are fragmentary views of turbine blades having modified-forms of a 29 detail of my invention; and i Fig. 5 is a fragmentary sectional view illustrating another modification of my invention. y a

In the design 'of axial flow elasticfluid turbines it has been found that where a gradually diverging motive fluid path is formed therethrough in the shape of a continuous cored cone, the turbine has higher efficiencies than where other known forms 80 are employed because such a flow path conforms more closely than do other forms to the specific volume of the motive fluid at each point in its expansion in the turbine and its shape is such that eddies are not 36 formed in the motive fluid flowto the extent foundin other designs. Disadvantages have been encountered in the manufacture of turbines designed with 'a motive fluid pathin the form ofacontinuous cored cone,

40 however, due to the fact that any axial displacement of the turbine rotor and the bladingor inaccuracy in'length or position, of blades, affects the radial clearances of the blades. This-disadvantage is present, espetscially in turbines of the double flow type,

embodying twocored conically shaped motive fluid: paths with opposed ends. "With such apparatus, axial displacement of the rotor increases the radial clearances of the 5 moving blades at one end of the turbine and decreases them at the otherend. Decreasing the radial clearances of thebladesentails danger of rubbing and. moving parts, while increasing the ra- Elec. & Manufacturing Company.

between the stationary site. the ends of the moving blads dial clearances withunshrouded blades in! creases the losses due to leakage over the ends of the blades.

My invention is therefore particularly applicableto turbinesof the double flow type and has for its particularobject to provide a turbine of the character. designated in which a slight axial displacementof the tur bine rotor or inaccuracy in length or lateral position of bladesdoes not adversely affect the operation of the turbine. In accordance with my invention, I provide a gradually diverging motive fluid path in the shape of a cored conical passage and'tprovide, opposite the ends of the blade rows, a seriesof offset. axially extending steps The roots of the blades or spacing pieces therebetween,

adjacentaninclined surface, are formed to conform with sald surface asshown and described in the application of Francis Hodgkinson, Serial N0.p688,29,6, filed January 24, 1.9241, andassigned to the Westinghouse With a cylinder and bladearrangement formed in this manner, the motive fluidis free to flow undisturbed in a gradually diverging. path through the turbine and thus permit the turbine to be operated 'at thehighest possible efliciency. a a Referring now to thedrawings for abett'er understanding of my invention I show in Fig. 1 at 10a fragment 'of a turbine casing enclosing a rotor 11. ;.As shown, the turbine is of the double flow type having amotivev fluid inlet at 12 from which the motive fluid flows in opposite directions to the exhaust as indicated at 13. The casing 10. is so formedflthat thepath of the. motive fluid passing therethrough forms two. cored cones with opposed ends as shown Garriedby the casing 10 are a plurality of rows of stationary blades 16 -16 which interleave and cooperatewith likerows of moving blades 17-17 carried by the rotor 11. The blade roots, or spacing piecesbetween the blades 16-16 are formed with inclined end surfaces as shown'at 18-: 18, adjacent the surfaceof the cylinder 10,1in order to conform to the conicalpath of the motive fluid. The moving blades 17-17 are arranged. so that their, ends extend beyond the inclined surface of the, blade roots or spacing pieces between the stationary blades 16--16. Oppo the cylinder 10 is bored so as to present a series of offset, axially extending steps 1919. lVith this arrangement it will be apparent that axial displacement of the rotor 11 within the limits of axial clearances does not affect the radial clearances of the moving blades 17-17. The rotor 11 is shown, for the purpose of illustration, as

having, for a part way, an approximately conical surface with axially extending steps 21-421 formed thereon opposite the ends of the associated stationary blades 16-16.

Referring to Figs. 2, 3 and 4, I show shrouding means for blades which may be employed to better providea continuous conical path for the motive fluid and which are adapted to minimize motive fluid leakage over the tops of the blades. In Fig. 2 a blade 31 having its tip so shaped as to aid in forming a conical path for the motive fluid is arranged to rotate opposite an axially extending surface 32. Provided on the blade 31 is a shroud 33 having upstanding sides forming packing members 34 and 36 with close radial clearance with respect to the surface 32. In Fig. 3 the shroud 33 has one upstanding edge 37 at one side of the blade and having close radial clearance with respectto'the surface 32. Fig. 4 is similar to Fig. 3 except that a packing member 38' is formed midway of the shroud 33 which prevents eccentric loading of the shroud when applied to moving blades. With either form of shrouding shown, the

' motive fluid is confined to its cored conical path in the turbine and motive fluid leakage over the blades is reduced to a minimum.

In Fig. 5, I show a blading having a. wellknown form of shrouding at 2626 designed to permit greater radial clearances of the blades and extending axially of the blades, as at 27-27, in order to minimize leakage of the motive fluid over the ends of the blades. With this form of blading the tips of the blades, either moving or stationary, or both, may be inclined and the shroudin'g forms therewith a conical path for the motive fluid. With this form, of course, the roots of the blades or spacing pieces between the blades are made with inclined surfaces 18 adjacent the blade carrying elements so as to cooperate in forming the conical motive fluid path. With this modification the axially extending surfaces opposite the tips of the blades are formed in the same manner as shown in Fig. 1.

From the foregoing it will be apparent that I have devised aturbine having a cored conical path for the motive fluid flowing therethrough and in which the adverse effects on operation caused by a slight axial displacement of the rotor are minimized.-

While I have shown my invention in severalfOrms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications, without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is 1. In a turbine, means providing in part a gradually diverging motive fluid flow passage, a blade having its longitudinal axis normal to the longitudinal axis of the turbine and having close radial clearance with respect to the opposed surface of the turbine, an offset portion extending parallel to the longitudinal axis of the turbine provided on the surface opposed to the blade,

and means carried by said blade and cooper ating with the first-mentioned means to define said diverging passage.

2. In a reaction turbine, the combination of relatively rotatable elements defining in part a gradually diverging motive fluid pas-' sage, interleaving rows of blades carried by the elements, longitudinally extending surfaces provided in the element describing the gradually diverging passage opposite each of the rows of blades carried by the other element, and means provided on the blades for minimizing leakage over the tips thereof, said means cooperating with the relatively rotatable elements to define a diverging passage.

3. In a double flow reaction turbine, the combination of a rotor and a stationary blade carrying element defining in part two cored frustro-conically shaped motive fluid passages with opposed ends, a. plurality of rows of moving blades carried by the rotor and having close radial clearance with re spect to the stationary blade carrying element, a plurality of rows of stationary blades mounted in the stationary blade carrying element and interleaving with the moving blades, offset portions provided in the frustro-conical surfaces to provide uniform radial clearances for the opposed blading, and shrouding on the blades opposite the frusto-conical surfaces forming continuations of said surfaces at the offset portions.

4. In a turbine, the combination of a plurality of rows of interleaving stationary and moving blades, a stationary blade carrying element having an interior contour forming in part the frustrum of a cone from which the blades protrude, arotor carrying the moving blades and defining with the stationary blade carrying element a cored frustroconically shaped passage for the motive fluid, surfaces extending in an axial direc-. 171011 provided in the stationary blade carrying element adjacent the tips of the moving blades, and shrouding on the moving blades cooperating with said stationary bladecarrying element to form the frustum of a cone.

5. In a turbine, the combination of a stationary blade carrying element having its blade holdingsurface inclined to the longitudinal axis of the turbine, a rotor carry- 5 ing a plurality of rows of moving blades and" defining with the stationary blade earrying element a motive fluid passage inclined to the longitudinal axis of the turbine, said stationary blade carrying element being machined in stepsextending in a longitudinal direction opposite the tips of each ofthe rows of moving blades, and means provided on the blades for minimizing leakage over the tips thereof, said means conface. I

In testimony whereof, I have hereunto subscribed my name this first day of October 1925.

JOSIAH F. JOHNSON.

forming to the contour of said inclined sur- 

